1. Field of the Invention
The present invention relates generally to reciprocating or piston engines (e.g., Rankine engines, internal combustion engines, etc.). More particularly, the present invention concerns a rotary valve assembly used to control intake and exhaust fluid flow to and from the cylinder(s) of the engine. The present invention also particularly concerns a seal for the rotary valve.
2. Discussion of Prior Art
Generally speaking, internal combustion engines traditionally include poppet valves for controlling fluid flow to and from each cylinder. Those ordinarily skilled in the art will appreciate that poppet valves rely on reciprocating valve stem movement to effect valve opening and closing. Such a configuration requires a complex drive for controlling valve stem movement (e.g., a camshaft). Furthermore, reciprocating valve and valve drive mechanism movement inherently involves cyclical, fatiguing operation. It is also known that poppet valves are particularly susceptible to wear and degradation caused by heat, which is attributable to certain components of the valve being continuously exposed to the chamber. Yet further, certain engine manufacturers have recognized the advantages of variable valve timing (e.g., increasing efficiency over a greater range of engine operation); however, variable valve timing with poppet valves has required expensive and complex valve drive arrangements. One such arrangement comprises a complex variable tension chain drive that is further deficient in the sense that it fails to provide significant flexibility in varying the valve timing.
In an apparent attempt to address the problems associated with poppet valves, there have been internal combustion engines provided with rotary valves that rotate in a single direction during engine operation to alternately block or permit flow along the intake or exhaust. It will be appreciated that the rotary valve is consequently not subjected to the fatigue problems often associated with a poppet valve. Furthermore, the rotating valve may be arranged so that no part thereof is continuously exposed to the chamber such that the risk of heat-caused wear and degradation is virtually eliminated. However, rotary valves for internal combustion engines have heretofore been very complex in construction. Furthermore, conventional rotary valves are believed to create high flow losses, thereby inhibiting flow to or from the engine. In addition, conventional rotary valves have not been provided with timing controls, and internal combustion engines having rotary valves therefore fail to provide variable valve timing.
It is noted that rotary valves have also been developed for other types of reciprocating engines, such as Rankine engines. Although some of these valves have been provided with timing controls, they too create high losses and consequently reduce engine efficiency.
Responsive to these and other problems, an important object of the present invention is to provide an improved rotary valve for a reciprocating engine. It is particularly an important object of the present invention to provide a rotary valve for a reciprocating engine, wherein the valve creates negligible flow losses and is simple, durable and inexpensive in construction. Another important object of the present invention is to provide a rotary valve having infinitely variable timing controls. It is also an important object of the present invention to provide an internal combustion engine that does not utilize poppet valves and permits variability of valve timing.
In accordance with these and other objects evident from the following description of the preferred embodiments, the present invention concerns a reciprocating engine including a body that presents an internal chamber and a fluid intake through which fluid flows to the chamber. Oscillating within the chamber during engine operation is a piston, and a rotary valve assembly fluidly disposed along the intake serves to generally block fluid flow to the chamber when closed and permit fluid flow to the chamber when open. The valve assembly presents a generally linear fluid flow passageway extending through the valve assembly, with the passageway being generally aligned and communicating with the intake when the valve assembly is open. The valve includes a rotatable valve body operable to intermittently block fluid flow through the passageway and thereby close the valve assembly as the valve body rotates. The valve assembly further includes a valve timing adjuster that is shiftable into and out of a variable flow-obstructing relationship with the passageway so as to vary the time during which the valve body blocks flow through the passageway.
The valve assembly preferably includes a cylindrical sleeve element and a cylindrical core element located concentrically within the sleeve. The cylindrical sleeve element presents diametrically opposed holes and the core element includes a diametrically extending surface that defines a diametrical flow-through opening. The holes and opening cooperatively define, when aligned, a generally linear fluid flow passageway through the valve assembly that is generally aligned with the intake when the valve assembly is open. One of the elements is rotatable during engine operation to intermittently block flow through the passageway and thereby close the valve assembly. Most preferably, the sleeve element comprises the rotating valve body and the core element is part of the valve timing adjuster. The present invention also concerns the valve assembly apart from the engine.
In addition, the present invention concerns a rotary valve seal assembly for providing sealed communication between the fluid flow opening in the rotatable cylindrical outer face of the valve assembly and a fluid flow port in the engine body. The valve assembly includes a pair of radially projecting flanges that extend continuously around the outer face with the opening located therebetween. The seal assembly includes a pair of elongated longitudinal seals extending longitudinally along the outer face of the valve assembly between the flanges and being generally fixed relative to the stationary surface with the fluid flow port being located therebetween. The longitudinal seals sealingly engage the outer face of the valve and the flanges. The seal assembly further includes a pair of arcuately shaped circumferential seals fixed relative to the stationary surface. The circumferential seals each sealingly engage a respective one of the flanges between the longitudinal seals. Finally, the inventive seal assembly includes a plurality of juncture seals each sealingly interconnected between a respective one of the longitudinal seals and a respective one of the circumferential seals, such that the seals cooperatively seal between the outer face and the stationary surface in a circumscribing relationship with the fluid flow port.
Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment and the accompanying drawing figures.